John Gill Commentary Proverbs 14:3

"In the mouth of the foolish is a rod for [his] pride; But the lips of the wise shall preserve them." — Proverbs 14:3 (ASV)

In the mouth of the foolish [is] a rod of pride
A proud tongue, or a tongue speaking proud and haughty things; with which foolish or wicked men smite others and wound and hurt their reputation and credit, and in the issue hurt themselves also; their tongue is not only a rod to others, but a scourge to themselves, or is the cause of evil coming upon them; such was the tongue of Pharaoh, as Jarchi on the place observes, (Exodus 5:2); and of those the psalmist speaks of, (Psalms 73:9); and particularly of antichrist, whose mouth is opened in blasphemies against God, and his tabernacle, and his saints, (Revelation 13:5Revelation 13:6).

but the lips of the wise shall preserve them ; from speaking such proud and haughty things against God and men; or from being hurt by the tongues of men or their own; yea, what coaxes out of their mouth is confounding and destructive to their enemies, (Revelation 11:5).